Abstract

Under very weak, nearly degenerate optical injection, laser diodes undergo amplitude and phase modulations that can be modeled by using the lumped-circuit rate equation approach. Population pulsations of the free carriers induce four-wave mixing between the injected optical field and the oscillating laser diode field. By measuring the amplitude modulation signal, regeneratively amplified input signal, and four-wave mixing signal, key diode parameters such as the carrier lifetime, relaxation resonance, and anti-guiding factor can be calculated. As the injection field is increased above this small signal regime the four-wave mixing signal saturates and broadens. Over certain detuning ranges, where the broadening is most pronounced, the nonlinear interaction can induce a longitudinal mode hop. Depending on the frequency difference between the injected optical field and the near-resonant laser mode, the laser diode will oscillate on one of the two longitudinal modes. Associated with this bistable operation is the appearance of a resonantly enhanced highly nondegenerate four-wave mixing signal on a third longitudinal mode.

© 1992 Optical Society of America